Microfluidic modulating valve

ABSTRACT

A valve is provided that can selectively change the size of a flow channel in a valve in order to modulate the fluid flow through the valve. In one illustrative embodiment, the valve includes a housing that defines a cavity, with an inlet and an outlet extending into the cavity. A diaphragm is positioned in the cavity, where at least part of the diaphragm defines at least part of the fluid path. One or more electrodes are fixed relative to the diaphragm, and one or more electrodes are fixed relative to the housing such that the diaphragm can be electrostatically actuated to modulate the fluid flow through the valve.

FIELD

The present invention generally relates to modulating valves, and more particularly, to microfluidic modulating valves that can selectively modulate the size of a flow channel.

BACKGROUND

Many modern industrial, commercial, aerospace, military and medical systems depend on reliable valves for fluid handling. The trends in fluid handling systems are toward smaller, more distributed and more portable systems for increasing uses in instrumentation and control. For example, microfluidic devices have become popular in such applications as analytical testing. In many cases, microfluidic devices are constructed in a multi-layer, often laminated, structure where each layer has channels and structures fabricated from a laminate material to form microscale voids or channels where fluids flow. The control and pumping of fluids through these channels is often affected by either external pressurized fluid forced into the laminate, or by structures located within the microfluidic device.

Many different types of valves for use in controlling fluids in such microscale devices have been developed. Many of these valves, however, are on-off type valves, and do not allow for the fluid flow to be modulated. What would be desirable, therefore, is a microfluidic modulating valve that can selectively modulate the size of a flow channel to allow for the fluid flow to be selectively modulated.

SUMMARY

The following summary of the invention is provided to facilitate an understanding of some of the innovative feature unique to the present invention and is not intended to be a full description. A full appreciation of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

The present invention generally relates to modulating valves, and more particularly, to electrostatically actuated microfluidic modulating valves that can selectively change the size of a flow channel in order to modulate the fluid flow through the valve. In one illustrative embodiment, a valve is provided that includes a housing that defines a cavity, with an inlet and an outlet extending into the cavity. A diaphragm is positioned in the cavity, where at least part of the diaphragm defines at least part of the fluid path. One or more electrodes are fixed relative to the diaphragm, and one or more electrodes are fixed relative to the housing such that the diaphragm can be electrostatically actuated between at least three stable positions, wherein each stable position results in a different cross-sectional area of the fluid path. In some embodiments, the various stable positions provide a cross-sectional area such that fluid can flow between the inlet port and the outlet port in at least two of the stable positions.

In some illustrative embodiments, the valve includes at least two independently controllable diaphragm electrodes fixed relative to the diaphragm, and at least one housing electrode fixed relative to the housing. When a sufficient voltage is applied between a first one of the diaphragm electrodes and the one or more housing electrode, at least part of the diaphragm is actuated to provide a first cross-sectional area for the fluid path. When a sufficient voltage is applied between a second one of the diaphragm electrodes (or a different combination of diaphragm electrodes) and one or more housing electrode, at least part of the diaphragm is actuated to provide a second cross-sectional area of the fluid path, wherein the first cross-sectional area is different from the second cross-sectional area.

Alternatively, or in addition, the valve may include at least two independently controllable housing electrode fixed relative to the housing, and at least one diaphragm electrode fixed relative to the diaphragm. When a sufficient voltage is applied between a first one of the housing electrodes and one or more diaphragm electrode, at least part of the diaphragm is actuated to provide a first cross-sectional area of the fluid path. When a sufficient voltage is applied between a second one of the housing electrodes (or a different combination of housing electrodes) and one or more diaphragm electrode, at least part of the diaphragm is actuated to provide a second cross-sectional area of the fluid path. In some embodiments, at least two of the housing electrodes are fixed relative to the housing on the same side of the diaphragm.

In some embodiments, the valve may include at least two housing electrodes fixed relative to a first one of two opposing sides of the cavity that includes the diaphragm, and at least two housing electrodes fixed relative to a second one of the two opposing sides of the cavity. In addition, the diaphragm may include at least two diaphragm electrodes fixed relative to the diaphragm, wherein at least selected diaphragm electrodes are adjacent to and generally aligned with two corresponding housing electrode; one on the first side of the cavity and the other on the second side of the cavity. When a sufficient voltage is applied between one or more of the diaphragm electrodes and one or more of the corresponding housing electrodes, at least part of the diaphragm is pulled toward the housing electrode. When a sufficient voltage is applied between different ones of the diaphragm electrodes and the other corresponding housing electrode, at least part of the diaphragm is pulled toward the different housing electrode. This may allow the cross-sectional area of the fluid path to be actively controlled. When multiple diaphragm electrodes/housing electrodes are controlled in this manner, the shape of the diaphragm, and thus the cross-sectional area of the fluid path, may be modulated over a relatively wide range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a top view of an illustrative normally open valve with equal area electrodes;

FIG. 2 is a schematic diagram of a front view of the illustrative embodiment of FIG. 1;

FIG. 3 is a schematic diagram of the side view of the illustrative embodiment of FIG. 1;

FIG. 4 is a schematic diagram of an alternative to the illustrative embodiment of FIG. 2 having the edges of the second electrode curve toward the diaphragm;

FIG. 5 is a schematic diagram of a top view of an illustrative normally open valve with binary patterned electrodes;

FIG. 6 is a schematic diagram of a front view of the illustrative embodiment of FIG. 5;

FIG. 7 is a schematic diagram of a side view of the illustrative embodiment of FIG. 5;

FIG. 8 is a schematic diagram of an alternative to the illustrative embodiment of FIG. 6 having the edges of the second electrode curve toward the diaphragm;

FIG. 9 is a schematic diagram of a top view of an illustrative normally closed valve with equal area electrodes;

FIG. 10 is a schematic diagram of a front view of the illustrative embodiment of FIG. 9;

FIG. 11 is a schematic diagram of a side view of the illustrative embodiment of FIG. 9;

FIG. 12 is a schematic diagram of an alternative to the illustrative embodiment of FIG. 10 having the edges of the second electrode curve toward the diaphragm;

FIG. 13 is a schematic diagram of a top view of an illustrative normally closed valve with binary patterned electrodes;

FIG. 14 is a schematic diagram of a front view of the illustrative embodiment of FIG. 13;

FIG. 15 is a schematic diagram of a side view of the illustrative embodiment of FIG. 13;

FIG. 16 is a schematic diagram of an alternative to the illustrative embodiment of FIG. 14 having the edges of the second electrode curve toward the diaphragm;

FIG. 17 is a schematic diagram of a front view of an illustrative valve including fluid flow valleys;

FIG. 18 is a schematic diagram of a side view of an illustrative valve seat;

FIG. 19 is a schematic diagram of a front view of the illustrative embodiment in FIG. 18;

FIG. 20 is a schematic diagram of a front view of an illustrative normally open valve that can increase or decrease the size of the flow chamber; and

FIG. 21 is a schematic diagram of FIG. 20, with the diaphragm activated in a partially open position.

DETAILED DESCRIPTION OF THE DRAWINGS

The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings show several embodiments which are meant to be illustrative of the claimed invention.

The present invention generally relates to modulating valves, and more particularly, to electrostatically actuated microfluidic modulating valves that can selectively change the size of a flow channel in order to help modulate the fluid flow through the valve. The term “fluid” as used herein includes liquids and/or gasses, as desired.

A first illustrative embodiment is shown in FIGS. 1, 2, and 3. FIG. 1 is a schematic diagram of a top view of an illustrative normally open valve in accordance with the present invention. FIG. 2 is a front view taken along 2-2 of FIG. 1, and FIG. 3 is a side view taken along 3-3 of FIG. 1.

The illustrative embodiment shown in FIGS. 1-3 includes a housing 8 that defines a cavity 14, with an inlet 10 and an outlet 12 extending into the cavity 14. A fluid path, such as fluid path 15, is selectively provided between the inlet 10 and outlet 12 through the cavity 14. A diaphragm 30 is positioned in the cavity 14, wherein at least part of the diaphragm 30 defines at least part of the fluid path 15. In the illustrative embodiment, the diaphragm 30 is positioned between two opposing sides 11 and 13 of the cavity 14. A number of diaphragm electrodes 20 are fixed relative to the diaphragm 30 as shown. The diaphragm electrodes 20 are spaced side-by-side in a spacing direction 17 along at least part of the diaphragm 30. In the illustrative embodiment, the flow path 15 extends normal (e.g. into the page in FIG. 2) or substantially normal to the spacing direction 17.

Specifically with reference to the illustrative embodiment of FIG. 2, a housing electrode 22 is fixed relative to opposing side 11 of housing 8. While only one housing electrode 22 is shown in FIG. 2, it is contemplated that more than one housing electrode 22 may be provided, if desired. When a voltage is applied between the housing electrode 22 and one or more selected diaphragm electrodes 20, the portion of the diaphragm that corresponds to the selected diaphragm electrodes 20 may be electrostatically pulled toward the housing electrode, thereby pinching off part of the flow path 15 through cavity 14. That is, by electrostatically pulling part of the diaphragm 30 toward the opposing side 11, the cross-sectional area of the flow path 15 may be reduced, which may modulate the fluid flow from the inlet 10 to the outlet 12 of the valve. In the illustrative embodiment, the diaphragm 30 may return to its un-activated position through elastic restoring forces.

In the illustrative embodiment, nine diaphragm electrodes 20 are shown. It is contemplated, however, that any suitable number of diaphragm electrodes 20 may be used, as desired. If none of the diaphragm electrodes 20 are electrostatically activated and pulled toward the opposing side 11, a maximum fluid flow cross-sectional area may be achieved between the inlet 10 and the outlet 12 of the valve. If one of the diaphragm electrodes 20 is electrostatically pulled toward the opposing side 11, a reduced fluid flow cross-sectional may be achieved between the inlet 10 and the outlet 12 of the valve. If two of the diaphragm electrodes 20 are electrostatically pulled toward the opposing side 11, an even further reduction in fluid flow cross-sectional area may be achieved between the inlet 10 and the outlet 12 of the valve, and so on. As can be seen, and depending on the number of diaphragm electrodes 20 that are provided and activated, a desired resolution in the modulated fluid flow through the valve may be achieved. In some illustrative embodiments, at least three stable diaphragm positions are provided, wherein fluid can flow from the inlet 10 to the outlet 12 in at least two of the stable positions.

The diaphragm electrodes 20 may be fixed to the diaphragm 30 and the housing electrode(s) 22 may be fixed to the housing 8 in any suitable manner. For example, the diaphragm electrodes 20 may be deposited on the diaphragm by evaporation or sputter deposition, doping the diaphragm 30 to be conductive in certain regions, screen printing a conductive material on the diaphragm, adhered an electrode pattern to the diaphragm 30, or in any other suitable manner. The one or more housing electrodes 22 may be provided in a different or similar manner, as desired. In some cases, part of all of the diaphragm or housing may be made from a conductive material, and may perform dual functions (e.g. as a housing and as an electrode), if desired.

In some cases, a dielectric layer may be provided over the diaphragm electrodes 20 and/or the housing electrode(s) 22. This may help prevent an electrical short between the diaphragm electrodes and the one or more housing electrodes when the diaphragm is pulled toward the housing electrodes during operation. The dielectric layer may also help protect the diaphragm electrodes and the one or more housing electrode(s) from the environment, and may further help prevent stiction.

To help reduce the voltage that may be required to begin closing the valve, and with reference to FIG. 4, it is contemplated the opposing wall 11 may be curved toward the diaphragm at one or more regions, such as in regions 40. Since the electrostatic force that is generated at a given voltage is inversely proportional to the distance between the electrodes, such a construction may help reduce the voltage required to initially pull the diaphragm 30 toward the opposing wall 11, at least in the regions 40. During operation of the valve shown in FIG. 4, a controller may initially provide a voltage between diaphragm electrode 20 a and housing electrode 23. This may pull the ends of the diaphragm down toward the opposing wall 11. This may also move the adjacent diaphragm electrodes closer to the housing electrode 23, which may also reduce the voltage that is required to pull the adjacent diaphragm electrodes toward the housing electrode 23, when desired. As can be seen, this may result in a “rolling” action of the diaphragm 30 as each successive diaphragm electrode is activated in sequence.

Another illustrative embodiment is shown in FIGS. 5, 6, and 7. FIG. 5 is a schematic diagram of a top view of an illustrative normally open valve with binary patterned electrodes. FIG. 6 is a front view taken along 6-6 of FIG. 5, and FIG. 7 is a side view taken along 7-7 of FIG. 5.

Similar to the previous illustrative embodiment, the illustrative embodiment shown in FIGS. 5-8 includes a housing 108 that defines a cavity 114, with an inlet 110 and an outlet 112 extending into the cavity 114. A fluid path, such as fluid path 115, is selectively provided between the inlet 110 and outlet 112 through the cavity 114. A diaphragm 130 is positioned in the cavity 114, wherein at least part of the diaphragm 130 defines at least part of the fluid path 115. In the illustrative embodiment, the diaphragm 130 is positioned between two opposing sides 111 and 113 of the cavity 114. A number of diaphragm electrodes 124 are fixed relative to the diaphragm 130 as shown. The diaphragm electrodes 124 are spaced side-by-side in a spacing direction 117 along at least part of the diaphragm 130. In the illustrative embodiment, the flow path 115 extends normal (e.g. into the page in FIG. 6) or substantially normal to the spacing direction 117.

The diaphragm electrodes 124 each have an electrode width along the spacing direction 117. In the illustrative embodiment, the diaphragm electrodes 124 have widths of 2^(N), where N represents the electrode position, from left to right, in the particular series of diaphragm electrodes. The advantage of having diaphragm electrodes 124 of different widths (e.g. 2^(N)) is the increase in the resulting range of flow areas that can be achieved. As shown in the illustrative embodiment, there are five diaphragm electrodes 124. By activating different combinations of diaphragm electrodes, the five diaphragm electrodes may provide thirty-two combinations of different fluid flow areas. It is contemplated, however, that any suitable width of the diaphragm electrodes 124 may be used or any suitable number of diaphragm electrodes 124 may be used, as desired.

Similar as discussed above, one or more housing electrode(s) 122 may be fixed relative to opposing side 111 of the housing 108. When a voltage is applied between the housing electrode 122 and selected diaphragm electrodes 124, the portion of the diaphragm 130 that corresponds to the selected diaphragm electrodes 124 may be electrostatically pulled toward the housing electrode 122, thereby pinching off part of the flow path 115 through cavity 114.

To help reduce the voltage that may be required to begin closing the valve, and with reference to FIG. 8, it is contemplated the opposing wall 11 may be curved toward the diaphragm 130 at one or more regions, such as in regions 140, as discussed above. Since the electrostatic force that is generated at a given voltage is inversely proportional to the distance between the electrodes, such a construction may help reduce the voltage required to initially pull the diaphragm 130 toward the opposing wall 111, at least in the regions 140.

A third illustrative embodiment is shown in FIGS. 9, 10, and 11. FIG. 9 is a schematic diagram of a top view of an illustrative normally closed valve in accordance with the present invention. FIG. 10 is a front view taken along 10-10 of FIG. 9, and FIG. 11 is a side view taken along 11-11 of FIG. 9.

The illustrative embodiment shown in FIGS. 9-11 includes a housing 208 that defines a cavity 214, with an inlet 210 and an outlet 212 extending into the cavity 214. A fluid path, such as fluid path 215, is selectively provided between the inlet 210 and outlet 212 through the cavity 214. A diaphragm 230 is positioned in the cavity 214, wherein at least part of the diaphragm 230 defines at least part of the fluid path 215. In the illustrative embodiment, the diaphragm 230 is positioned between two opposing sides 211 and 213 of the cavity 214. A number of diaphragm electrodes 220 are fixed relative to the diaphragm 230 as shown. The diaphragm electrodes 220 are spaced side-by-side in a spacing direction 217 along at least part of the diaphragm 230. In the illustrative embodiment, the flow path 215 extends normal (e.g. into the page in FIG. 10) or substantially normal to the spacing direction 217.

Specifically with reference to FIG. 10, a housing electrode 222 may be fixed relative to opposing side 213 of housing 208. While only one housing electrode 222 is shown in FIG. 10, it is contemplated that more than one housing electrode 222 may be provided, if desired. In the illustrative embodiment, at least one biasing element 235 is provided between the number of diaphragm electrodes 220 and the housing electrode 222, as shown. In one case, each biasing element 235 may include a spring. However, the biasing element may be any suitable biasing means that is capable of biasing the diaphragm 230 toward opposing side 211 of cavity—in the normally closed valve configuration. In some cases, the biasing means may simply be the elastic properties of the diaphragm 230 itself. That is, the diaphragm 230 may be mounted (and possibly stretched) directly adjacent to the opposing side 211 of cavity. The diaphragm 230 may then return to this position by elastic restoring forces when the electrodes are not activated.

As illustrated in FIG. 10, there are nine diaphragm electrodes 220 each with a biasing element 235. It is contemplated, however, that there may be any number of diaphragm electrodes 220. It is also contemplated, that there may be any number of biasing elements 235 between the diaphragm electrode 220 and the housing electrode 222, as desired.

The biasing elements 235 exert a force between the number of diaphragm electrodes 220 and the housing electrode 222. The biasing force helps push the diaphragm 230 towards the housing wall 211 pinching off the flow path 215 through the cavity 214. When a voltage is applied between the housing electrode 222 and one or more of the diaphragm electrodes 220, a force is generated between the housing electrode 222 and the activated diaphragm electrodes 220, which overcomes the biasing force provided by the corresponding biasing elements 235. Thus, the portion of the diaphragm that corresponds to the selected diaphragm electrodes 220 may be electrostatically pulled toward the housing electrode 222, thereby opening part of the flow path 215 through cavity 214. That is, by electrostatically pulling part of the diaphragm 230 toward the opposing side 213, the cross-sectional area of the flow path 215 may be increased, which may modulate the fluid flow from the inlet 210 to the outlet 212 of the valve.

If none of the diaphragm electrodes 220 are electrostatically pulled toward the opposing side 213, a minimum fluid flow (in some cases no fluid flow) may be achieved between the inlet 210 and the outlet 212 of the valve. If one of the diaphragm electrodes 220 is electrostatically pulled toward the opposing side 213 overcoming the corresponding biasing element, an increased fluid flow may be achieved between the inlet 210 and the outlet 212 of the valve. If two of the diaphragm electrodes 220 are electrostatically pulled toward the opposing side 213, an even further increase in fluid flow may be achieved between the inlet 210 and the outlet 212 of the valve, and so on. As can be seen, and depending on the number of diaphragm electrodes 220 that are provided and activated, a desired resolution in the modulated fluid flow through the valve may be achieved. In some illustrative embodiments, at least three stable diaphragm positions are provided, wherein fluid can flow from the inlet 210 to the outlet 212 in at least two of the stable positions. One stable diaphragm 230 position may be fully closed, one may be fully open, and yet another may be partially open.

To help reduce the voltage that may be required to begin closing the valve, and with reference to FIG. 12, it is contemplated the opposing wall 213 may be curved toward the diaphragm 230 at one or more regions, such as regions 240. Since the electrostatic force that is generated at a given voltage is inversely proportional to the distance between the electrodes, such a construction may help reduce the voltage required to initially pull the diaphragm 230 toward the opposing wall 213, at least in the regions 240.

During operation of the valve shown in FIG. 12, a controller may initially provide a voltage between diaphragm electrodes 220 a and housing electrode 223. This may pull the ends of the diaphragm 230 toward the opposing wall 213 overcoming the corresponding biasing elements 235. This may also move the adjacent diaphragm electrodes 220 closer to the housing electrode 223, which may reduce the voltage that is required to pull the adjacent diaphragm electrodes 220 toward the housing electrode 223, when desired. As can be seen, this may result in a “rolling” action of the diaphragm 230 as each successive diaphragm electrode 220 is activated in sequence.

A fourth illustrative embodiment is shown in FIGS. 13, 14, and 15. FIG. 13 is a schematic diagram of a top view of an illustrative normally closed valve with binary patterned electrodes. FIG. 14 is a front view taken along 14-14 of FIG. 13, and FIG. 15 is a side view taken along 15-15 of FIG. 13.

Similar to the previous embodiment, the illustrative embodiment shown in FIGS. 13-15 includes a housing 308 that defines a cavity 314, with an inlet 310 and an outlet 312 extending into the cavity 314. A fluid path, such as flow path 315, is selectively provided between the inlet 310 and outlet 312 through the cavity 314. A diaphragm 330 is positioned in the cavity 314, wherein at least part of the diaphragm 330 defines at least part of the fluid path 315. In the illustrative embodiment, the diaphragm 330 is positioned between two opposing sides 311 and 313 of the cavity 314. A number of diaphragm electrodes 320 are fixed relative to the diaphragm 330 as shown. The diaphragm electrodes 320 are spaced side-by-side in a spacing direction 317 along at least part of the diaphragm 330. A biasing element 335 is fixed between diaphragm 330 and the housing 308, as shown. In the illustrative embodiment, the flow path 315 extends normal (e.g. into the page in FIG. 14) or substantially normal to the spacing direction 317.

The diaphragm electrodes 324 each have an electrode width along the spacing direction 317. In the illustrative embodiment, the diaphragm electrodes 324 have widths of 2^(N), where N represents the electrode position, from left to right, in the particular series of diaphragm electrodes. The advantage of having diaphragm electrodes 324 of different widths (e.g. 2^(N)) is the increase in the resulting range of flow areas that can be achieved. As shown in the illustrative embodiment, there are five diaphragm electrodes 324. By activating different combinations of diaphragm electrodes 324, the five diaphragm electrodes may provide thirty-two combinations of different fluid flow areas. It is contemplated, however, that any suitable width of the diaphragm electrodes 324 may be used or any suitable number of diaphragm electrodes 324 may be used, as desired.

Specifically with reference to FIG. 14, a housing electrode 322 may be fixed relative to opposing side 313 of housing 308. While only one housing electrode 322 is shown in FIG. 14, it is contemplated that more than one housing electrode 322 may be provided, if desired. At least one biasing element 335 is positioned between the number of diaphragm electrodes 320 and the housing electrode 322. In one case, the biasing element 335 may include a spring, however, the biasing element may be any suitable biasing element as desired. As illustrated in FIG. 14, there are nine diaphragm electrodes 320 each with one or more biasing element. It is contemplated, however, that there may be any number of diaphragm electrodes 320. It is also contemplated, that there may be more than one biasing elements 335 for each diaphragm electrodes 320 as desired.

The biasing elements 335 exert a force between the corresponding diaphragm electrodes 320 and the housing 308. The biasing force pushes the diaphragm 330 towards the housing wall 311 pinching off the flow path 315 through the cavity 314. When a voltage is applied between the housing electrode 322 and one or more selected diaphragm electrodes 320, a force is generated between the housing electrode 322 and the selected diaphragm electrodes 320 to overcome the biasing force. The portion of the diaphragm that corresponds to the selected diaphragm electrodes 320 is electrostatically pulled toward the housing electrode 322, thereby opening part of the flow path 315 through cavity 314. That is, by electrostatically pulling part of the diaphragm 330 toward the opposing side 313, the cross-sectional area of the flow path 315 may be increased, which may modulate the fluid flow from the inlet 310 to the outlet 312 of the valve.

If none of the diaphragm electrodes 320 are electrostatically pulled toward the opposing side 313, a minimum fluid flow (in some cases no fluid flow) may be achieved between the inlet 310 and the outlet 312 of the valve. If one of the diaphragm electrodes 320 is electrostatically pulled toward the opposing side 313 overcoming the biasing means, an increased fluid flow may be achieved between the inlet 310 and the outlet 312 of the valve. If two of the diaphragm electrodes 320 are electrostatically pulled toward the opposing side 313, an even further increase in fluid flow may be achieved between the inlet 310 and the outlet 312 of the valve, and so on. As can be seen, and depending on the number and type of diaphragm electrodes 320 that are provided and activated, a desired resolution in the modulated fluid flow through the valve may be achieved. In some illustrative embodiments, at least three stable diaphragm positions are provided, wherein fluid can flow from the inlet 310 to the outlet 312 in at least two of the stable positions.

To help reduce the voltage that may be required to begin closing the valve, and with reference to FIG. 16, it is contemplated the opposing wall 313 may be curved toward the diaphragm 330 at one or more regions, such as regions 340. Since the electrostatic force that is generated at a given voltage is inversely proportional to the distance between the electrodes, such a construction may help reduce the voltage required to initially pull the diaphragm 330 toward the opposing wall 313, at least in the regions 340.

Another illustrative embodiment is shown in FIG. 17. FIG. 17 is a schematic diagram of a cross-sectional view of a normally open valve including fluid flow valleys. The illustrative embodiment includes a housing 408, with an inlet 412 and outlet 412 extending into the cavity 414. A diaphragm 430 is positioned in the cavity 414, wherein at least part of the diaphragm 430 defines at least part of the fluid path. The housing wall 429 has a corrugated surface having alternating ridges 431 and groves 432. A number of diaphragm electrodes 420 are fixed relative to the diaphragm 430 as shown. The diaphragm electrodes 420 are spaced relative to the corrugated surface of the housing wall 429. It is contemplated that the width of the ridges 431 and groves 432 may be any width as desired and that the corresponding one or more diaphragm electrodes 420 may have a similar width. A housing electrode (not shown) may be fixed to the corrugated surface of the housing wall 429. The diaphragm electrodes 420 and the corrugated surface form fluid “flow valleys.”

When a voltage is applied between the housing electrode (not shown) and one or more selected diaphragm electrodes 420, the portion of the diaphragm 430 that corresponds to the selected diaphragm electrodes 420 may be electrostatically pulled toward the housing electrode, thereby pinching off at least part of the flow valley through cavity 414 to modulate the flow. The advantage of having individual fluid flow valleys for each diaphragm electrode 420 is that as the diaphragm 430 is pulled toward housing wall 429, the corrugated surface may provide a better seal of the cavity 414. Thus, the leakage of the valve may be decreased. This embodiment may be incorporated with any of the previous embodiments to improve the performance of the valves.

Another illustrative embodiment is shown in FIGS. 18 and 19. FIG. 18 is a schematic diagram of a side view of an illustrative valve seat. FIG. 19 is a front view of the embodiment in FIG. 18.

The illustrative embodiment shown in FIGS. 18 and 19 includes a housing 608 that defines a cavity 614, with an inlet 610 and outlet 612. A diaphragm 640 is position in the cavity 614, wherein at least part of the diaphragm 630 defines part of the fluid path. A number of diaphragm electrodes 620 are fixed relative to the diaphragm 630. The diaphragm electrodes are spaced side-by-side in a spacing direction 617 along at least part of the diaphragm 630. In the illustrative embodiment, a bias element is fixed between diaphragm 630 and the housing 408. The bias element 635 may be a spring or any other suitable bias means, as desired. In the illustrative embodiment, outlet 612 extends into the cavity. At least one diaphragm electrode 625, is a “valve seat” electrode. The one or more valve seat electrode 625 is situated over the outlet 612. The one or more valve seat electrode 625 is biased to push the diaphragm 630 over the outlet 612 to form a seal.

In operating the valve in the illustrative embodiment, the one or more valve seat electrode 625 may help control the opening and closing of the valve. The other diaphragm electrodes 620 may be used to modulate the flow of the fluid through the cavity 614 when the valve is open. When a voltage is applied to the one or more valve seat electrode 625, the diaphragm is pulled toward the housing electrode 422 opening the outlet 612 allowing fluid to flow. When a voltage is applied to the other diaphragm electrodes 620, the part of the diaphragm corresponding to the selected diaphragm electrodes 620 is pulled toward the housing electrode 422, thereby modulating the flow of fluid from the inlet 610 to the outlet 612. This embodiment may used in conjunction with any of the previous embodiments.

Another illustrative embodiment is shown in FIGS. 20 and 21. FIG. 20 is a schematic diagram of a side view of a normally open valve that can increase or decrease the size of the cavity 514. FIG. 21 is a schematic diagram of FIG. 20, with the diaphragm activated in a partially open position.

The illustrative embodiment includes a housing 508 that defines a cavity 514, with an inlet 510 and outlet 512 extending into the cavity 514. A diaphragm 530 is positioned in the cavity 514, wherein at least part of the diaphragm defines at least part of the fluid path. The diaphragm 530 is positioned between the two opposing sides of the cavity 511 and 513. A number of diaphragm electrodes 520 are fixed relative to the diaphragm 530 as shown. The diaphragm electrodes 520 are spaced along 517 of the diaphragm 530. The opposing cavity walls 511 and 513 each have housing electrodes 522 and 526 fixed to them. The housing electrodes 522 and 526 are shown similarly spaced along 517 as the diaphragm electrodes. It is contemplated that the diaphragm electrodes 520 and the housing electrodes 522 and 526 may be any width or spacing, as desired. Also, it is contemplated that the housing electrodes 522 and 526 may be continuous electrodes, as shown by dotted lines 540 and 542, rather than spaced electrodes. Alternatively, the housing electrodes 522 and 526 may be spaced electrodes, and the diaphragm electrodes 520 may be a continuous electrode, if desired.

To modulate the flow, a voltage may be applied to one or more selected diaphragm electrodes 520 and one or more housing electrodes 522 and 526. When a voltage is applied to one or more selected diaphragm electrodes 520 and one or more selected housing electrodes 522, the part of the diaphragm 530 corresponding to the diaphragm electrode 520 may be electrostatically pulled toward the housing electrode 522, thereby increasing the flow path of the cavity 514. When a voltage is applied to one or more selected diaphragm electrodes 520 and one or more selected housing electrodes 526, the part of the diaphragm 530 corresponding to the selected diaphragm electrode 520 may be electrostatically pulled toward the housing electrode 526, thereby decreasing the size of the flow path.

It is contemplated that one or more housing electrodes 522 and one or more housing electrodes 526 may be actuated at the same time pulling part of the diaphragm 530 up and pulling another part of the diaphragm 530 down, as shown in FIG. 21. However, a selected diaphragm electrode 520 may be actuated with either corresponding housing electrode 522 or 526. Thus, the flow can be modulated to increase or decrease the fluid flow in the cavity 514.

When the housing electrodes 522 and 526 are continuous electrodes, as shown by dotted lines 540 and 542, and in one illustrative embodiment, a positive voltage such as +A volts may be applied to the upper housing electrode 522, and a negative voltage such as −A volts may be applied to the lower housing electrode 526. Initially, the diaphragm electrodes 520 may be a zero volts. To modulate the flow, a positive voltage, such as +A volts, may be applied to one or more selected diaphragm electrodes 520 to move the corresponding diaphragm electrodes 520 toward the −A voltage of the lower housing electrode 526. Likewise, a negative voltage, such as −A volts, may be applied to one or more selected diaphragm electrodes 520 to move the corresponding diaphragm electrodes 520 toward the +A voltage of the upper housing electrode 522.

Having thus described the preferred embodiments of the present invention, those of skill in the art will readily appreciate that yet other embodiments may be made and used within the scope of the claims hereto attached. Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respect, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of parts without exceeding the scope of the invention. The invention's scope is, of course, defined in the language in which the appended claims are expressed. 

1. A valve, comprising: a housing that defines a cavity; an inlet port in fluid communication with the cavity; an outlet port in fluid communication with the cavity; a fluid path within the cavity that extends between the inlet port and the outlet port, the fluid path having a cross-sectional area; a diaphragm positioned in the cavity, at least part of the diaphragm defining at least part of the fluid path; and means for electrostatically actuating at least part of the diaphragm between at least three stable positions, wherein each stable position results in a different cross-sectional area of the fluid path, and wherein the different cross-sectional areas are sized such that fluid can flow between the inlet port and the outlet port in at least two of the stable positions.
 2. The valve of claim 1 wherein the cavity is at least partially defined by two opposing sides.
 3. The valve of claim 2 wherein the means for electrostatically actuating at least part of the diaphragm includes one or more electrodes fixed relative to the diaphragm and one or more electrodes fixed relative to one or more of the two opposing sides.
 4. The valve of claim 3 wherein the means for electrostatically actuating at least part of the diaphragm includes two or more electrodes fixed relative to the diaphragm and one or more electrodes fixed relative to one or more of the two opposing sides.
 5. The valve of claim 3 wherein the means for electrostatically actuating at least part of the diaphragm includes one or more electrodes fixed relative to the diaphragm and two or more electrodes fixed relative to at least one of the two opposing sides.
 6. The valve of claim 3 wherein the means for electrostatically actuating at least part of the diaphragm includes two or more electrodes fixed relative to the diaphragm and two or more electrodes fixed relative to each of the two opposing sides.
 7. The valve of claim 2 wherein at least one of the two opposing sides includes a portion that extends down closer to the diaphragm.
 8. The valve of claim 7 wherein the portion that extends down closer to the diaphragm includes an electrode.
 9. The valve of claim 8 wherein a part of the diaphragm adjacent to the portion of the at least one of the two opposing sides that extends down closer to the diaphragm includes an electrode.
 10. The valve of claim 1 wherein at least part of at least one of the two opposing sides is corrugated having alternating ridges and grooves.
 11. The valve of claim 10 wherein the means for electrostatically actuating at least part of the diaphragm includes one or more electrodes fixed relative to the corrugated side(s).
 12. The valve of claim 11 wherein the means for electrostatically actuating at least part of the diaphragm includes one or more spaced electrodes fixed relative to the diaphragm, wherein at least selected spaced electrodes are positioned adjacent to corresponding grooves in the corrugated side(s).
 13. The valve of claim 3 further comprising a biasing element for biasing the diaphragm away from one of the two opposing sides.
 14. The valve of claim 13 wherein the biasing element comprises a spring.
 15. The valve of claim 14 wherein the biasing element comprises two or more springs.
 16. The valve of claim 13 wherein the biasing element bias the diaphragm in a position that closes or substantially closes the fluid path
 17. The valve of claim 1 wherein one of the at least three stable positions is a fully closed position.
 18. The valve of claim 17 wherein one of the at least three stable positions is a fully open position.
 19. The valve of claim 18 wherein one of the at least three stable positions is a partially open position.
 20. The valve of claim 1 wherein one of the at least three stable positions is a first partially open position, and another of the at least three stable positions is a second but different partially open position.
 21. A valve, comprising: a housing that defines a cavity; an inlet port in fluid communication with the cavity; an outlet port in fluid communication with the cavity; a fluid path within the cavity that extends between the inlet port and the outlet port, the fluid path having a cross-sectional area; a diaphragm positioned in the cavity, at least part of the diaphragm defining at least part of the fluid path; and at least two independently controllable diaphragm electrodes fixed relative to the diaphragm; and at least one housing electrode fixed relative to the housing; the at least two diaphragm electrodes and the at least one housing electrode configured such that when a sufficient voltage is applied between a first one of the diaphragm electrodes and the at least one housing electrode at least part of the diaphragm is actuated to provide a first cross-sectional area of the fluid path, and when a sufficient voltage is applied between a second one of the diaphragm electrodes and the at least one housing electrode at least part of the diaphragm is actuated to provide a second cross-sectional area of the fluid path.
 22. The valve of claim 21 wherein the at least two independently controllable diaphragm electrodes are spaced side-by side in a spacing direction along at least part of the diaphragm.
 23. The valve of claim 22 wherein the flow path extends normal or substantially normal to the spacing direction.
 24. The valve of claim 22 wherein the at least two independently controllable diaphragm electrodes each have an electrode width along the spacing direction, and at least two of the electrodes have different electrode widths.
 25. The valve of claim 24 wherein a series of the at least two independently controllable diaphragm electrodes have electrode widths of 2^(N), where N represents a series number of a particular electrode in the series of electrodes.
 26. The valve of claim 22 wherein the at least two independently controllable diaphragm electrodes each have an electrode width along the spacing direction, and wherein the at least two electrodes have the same or substantially the same electrode widths.
 27. The valve of claim 21 further comprising a biasing element for biasing the diaphragm away from the at least one housing electrode.
 28. The valve of claim 27 wherein the biasing element comprises a spring.
 29. The valve of claim 28 wherein the biasing element comprises two or more springs.
 30. The valve of claim 28 wherein the biasing element comprises a spring for each of the at least two independently controllable diaphragm electrodes.
 31. A valve, comprising: a housing that defines a cavity, wherein the cavity is at least partially defined by two opposing sides; an inlet port in fluid communication with the cavity; an outlet port in fluid communication with the cavity; a fluid path within the cavity that extends between the inlet port and the outlet port, the fluid path having a cross-sectional area; a diaphragm positioned in the cavity between the two opposing sides of the cavity, at least part of the diaphragm defining at least part of the fluid path; and at least two independently controllable housing electrode fixed relative to one of the two opposing sides that define the cavity; at least one diaphragm electrode fixed relative to the diaphragm; and the at least one diaphragm electrode and the at least two housing electrodes configured such that when a sufficient voltage is applied between a first one of the housing electrodes and the at least one diaphragm electrode at least part of the diaphragm is actuated to provide a first cross-sectional area of the fluid path, and when a sufficient voltage is applied between a second one of the housing electrodes and the at least one diaphragm electrode at least part of the diaphragm is actuated to provide a second cross-sectional area of the fluid path.
 32. The valve of claim 31 wherein the at least two independently controllable housing electrodes are spaced side-by side in a spacing direction along at least part of the housing.
 33. The valve of claim 32 wherein the flow path extends normal or substantially normal to the spacing direction.
 34. The valve of claim 32 wherein the at least two independently controllable housing electrodes each have an electrode width along the spacing direction, and at least two of the electrodes have different electrode widths.
 35. The valve of claim 34 wherein a series of the at least two independently controllable housing electrodes have electrode widths of 2^(N), where N represents a series number of a particular electrode in the series of electrodes.
 36. The valve of claim 32 wherein the at least two independently controllable housing electrodes each have an electrode width along the spacing direction, and wherein the at least two electrodes have the same or substantially the same electrode widths.
 37. The valve of claim 31 further comprising a biasing element for biasing the diaphragm away from the at least two housing electrodes.
 38. The valve of claim 37 wherein the biasing element comprises a spring.
 39. The valve of claim 38 wherein the biasing element comprises two or more springs.
 40. The valve of claim 38 wherein the biasing element comprises a spring for each of the at least two independently controllable housing electrodes.
 41. A valve, comprising: a housing that defines a cavity, wherein the cavity is at least partially defined by two opposing sides; an inlet port in fluid communication with the cavity; an outlet port in fluid communication with the cavity; a fluid path within the cavity that extends between the inlet port and the outlet port, the fluid path having a cross-sectional area; a diaphragm positioned in the cavity between the two opposing sides of the cavity, at least part of the diaphragm defining at least part of the fluid path; and at least two housing electrodes fixed relative to a first one of the two opposing sides and at least two housing electrodes fixed relative to a second one of the two opposing sides; at least two diaphragm electrodes fixed relative to the diaphragm; and at least selected ones of the at least two diaphragm electrodes each corresponding to an electrode on the first one of the two opposing sides and an electrode on the second one of the two opposing sides.
 42. The valve of claim 41 wherein the diaphragm is positioned in the cavity and is spaced from both the two opposing sides of the cavity.
 43. A method for modulating a fluid flow through a fluid path, the method comprising the steps of: selecting a cross-sectional area for the fluid path from three or more discrete cross-sectional area values; and changing the cross-sectional area for the fluid path to the selected one of the three or more discrete cross-sectional area values. 